Mobile communication terminal, information processing method, data processing program, and recording medium

ABSTRACT

A transmitter cell phone  10  is provided with a controller  11  for fulfilling functions of a data encryptor, a first key encryptor, and an encryption file generator. The data encryptor encrypts data, using a first encryption key. The first key encryptor encrypts the first encryption key, using a second encryption key. The encryption file generator generates an encryption file of the data from the data encrypted by the data encryptor, the first encryption key encrypted by the first key encryptor, and user-specific information permitting identification of a user of the mobile communication terminal.

TECHNICAL FIELD

The present invention relates to a mobile communication terminal, aninformation processing method, a data processing program, and arecording medium.

BACKGROUND ART

In recent years, the development of information communicationtechnologies promoted transmission and reception of data of documents,pictures, etc. through networks such as the Internet. Particularly, inthe case of communication terminals such as cell phones, where a userswitches a model to another or where a user selectively uses a pluralityof communication terminals, data such as information about the user, atelephone directory, etc. is transferred to another communicationterminal, for example, upon replacement of UIM (User Identity Module).During the transfer of data, conversion (encryption) of the dataaccording to a predetermined rule is an effective means for preventingunauthorized access to the data or falsification of the data by a thirdparty in the middle of communication.

DISCLOSURE OF THE INVENTION

However, the conventional techniques as described above had thefollowing problem. Namely, encryption key data (hereinafter referred toas “encryption key”) is used in encryption of the data, but it is alsopresumable that the encryption of data by the encryption key is notalways effective in preventing such irregularities as the unauthorizedaccess to or falsification of data by a third party, because ofsophistication of data analysis technologies.

The present invention has been accomplished in view of the above problemand an object of the invention is to provide a mobile communicationterminal, an information processing method, a data processing program,and a recording medium capable of making the analysis of encrypted datadifficult and thus securing high confidentiality for data.

In order to achieve the above object, a mobile communication terminalaccording to the present invention comprises: data encrypting means forencrypting data (which encompasses a file and/or a program and which canbe single data or multiple data) stored in the mobile communicationterminal, using a first encryption key; first key encrypting means forencrypting the first encryption key, using a second encryption key; andencryption file generating means for generating an encryption file ofthe data from the data encrypted by the data encrypting means, the firstencryption key encrypted by the first key encrypting means, anduser-specific information permitting identification of a user of themobile communication terminal, for generation of the second encryptionkey.

In order to achieve the above object, an information processing methodaccording to the present invention is an information processing methodfor a mobile communication terminal to process data, the informationprocessing method comprising: a data encryption step of encrypting data,using a first encryption key; a first key encryption step of encryptingthe first encryption key, using a second encryption key; and anencryption file generation step of generating an encryption file of thedata from the data encrypted in the data encryption step, the firstencryption key encrypted in the first key encryption step, anduser-specific information permitting identification of a user of themobile communication terminal, for generation of the second encryptionkey.

In order to achieve the above object, a data processing programaccording to the present invention is a data processing program forletting a computer fulfill: a data encryption function of encryptingdata, using a first encryption key; a first key encryption function ofencrypting the first encryption key, using a second encryption key; andan encryption file generation function of generating an encryption fileof the data from the data encrypted by the data encryption function, thefirst encryption key encrypted by the first key encryption function, anduser-specific information permitting identification of a user of amobile communication terminal, for generation of the second encryptionkey.

According to these aspects of the invention, the encryption file of thedata is generated from the data encrypted using the first encryptionkey, the first encryption key encrypted using the second encryption key,and the user-specific information for generation of the secondencryption key. Namely, the encryption file is generated through doubleencryption processes, so that the analysis of the data is made moredifficult than that of encryption files encrypted using a non-encryptedencryption key. This can prevent such irregularities as the unauthorizedaccess to or falsification of the data by a third party in advance. As aresult, high confidentiality can be secured for the data. Since thegenerated encryption file contains the user-specific informationpermitting identification of the user of the mobile communicationterminal, it is at low risk of being decrypted by mobile communicationterminals of other users.

In order to achieve the above object, another potential mobilecommunication terminal according to the present invention comprises dataencrypting means for encrypting data, using a first encryption key;first falsification check data generating means for generating firstfalsification check data for a falsification check on the encrypteddata; additional information encrypting means for encrypting additionalinformation containing the first falsification check data generated bythe first falsification check data generating means, using a secondencryption key; and encryption file generating means for generating anencryption file of the data from the data encrypted by the dataencrypting means, the additional information encrypted by the additionalinformation encrypting means, and second encryption key informationcontaining user-specific information permitting identification of a userof the mobile communication terminal.

In order to achieve the above object, another potential informationprocessing method according to the present invention is an informationprocessing method for a mobile communication terminal to process data,the information processing method comprising: a data encryption step ofencrypting data, using a first encryption key; a first falsificationcheck data generation step of generating first falsification check datafor a falsification check on the encrypted data; an additionalinformation encryption step of encrypting additional informationcontaining the first falsification check data generated in the firstfalsification check data generation step, using a second encryption key;and an encryption file generation step of generating an encryption fileof the data from the data encrypted in the data encryption step, theadditional information encrypted in the additional informationencryption step, and second encryption key information containinguser-specific information permitting identification of a user of themobile communication terminal.

In order to achieve the above object, another potential data processingprogram according to the present invention is a data processing programfor letting a computer fulfill: a data encryption function of encryptingdata, using a first encryption key; a first falsification check datageneration function of generating first falsification check data for afalsification check on the encrypted data; an additional informationencryption function of encrypting additional information containing thefirst falsification check data generated by the first falsificationcheck data generation function, using a second encryption key; and anencryption file generation function of generating an encryption file ofthe data from the data encrypted by the data encryption function, theadditional information encrypted by the additional informationencryption function, and second encryption key information containinguser-specific information permitting identification of a user of amobile communication terminal.

According to these aspects of the invention, the encryption file of thedata is generated from the data encrypted using the first encryptionkey, the additional information containing the first falsification checkdata for a falsification check on the encrypted data, and theuser-specific information. Namely, the generated encryption filecontains both the encrypted data and the data encrypted after havingbeen converted for the falsification check, which makes the analysis ofthe data difficult. This can prevent the irregularities such as theunauthorized access to or falsification of the data by a third party. Asa result, high confidentiality can be secured for the data. Since thegenerated encryption file contains the user-specific informationpermitting identification of the user of the mobile communicationterminal, it is at low risk of being decrypted by mobile communicationterminals of other users.

Preferably, the mobile communication terminal according to the presentinvention further comprises second key generating means for generatingthe second encryption key, using the second encryption key information.

Preferably, the information processing method according to the presentinvention further comprises a second key generation step wherein themobile communication terminal generates the second encryption key, usingthe second encryption key information.

Preferably, the data processing program according to the presentinvention makes the computer further fulfill a second key generationfunction of generating the second encryption key, using the secondencryption key information.

According to these aspects of the invention, the second encryption keyis generated using the second encryption key information containing theuser-specific information permitting the identification of the user ofthe mobile communication terminal. The additional information containingthe falsification check data is encrypted using the second encryptionkey. Namely, the user-specific information is essential to decryption ofthe additional information. Accordingly, the encryption file is at lowrisk of being decrypted by mobile communication terminals of otherusers, as a matter of course, and the additional information is also atlow risk of being decrypted by mobile communication terminals of otherusers. This secures much higher confidentiality for the data.

More preferably, the mobile communication terminal according to thepresent invention is constructed in a configuration wherein the secondencryption key information contains identification information foridentification of an algorithm used in generation of the secondencryption key and wherein the second key generating means generates thesecond encryption key, using the algorithm identified by theidentification information.

More preferably, the information processing method according to thepresent invention is configured so that the second encryption keyinformation contains identification information for identification of analgorithm used in generation of the second encryption key and so thatthe second key generation step comprises a step wherein the mobilecommunication terminal generates the second encryption key, using thealgorithm identified by the identification information.

More preferably, the data processing program according to the presentinvention is configured so that the second encryption key informationcontains identification information for identification of an algorithmused in generation of the second encryption key and so that the secondkey generating function is arranged to fulfill a function of generatingthe second encryption key, using the algorithm identified by theidentification information.

According to these aspects of the invention, the second encryption keyis generated using the algorithm identified by the identificationinformation included in the second encryption key information. Namely,the mobile communication terminal properly selects the algorithm forgeneration of the second encryption key, according to a type of thesecond encryption key information. Accordingly, it becomes moredifficult for a third party to specify the algorithm used in thegeneration of the second encryption key than in the case where thesecond encryption key is always generated by an identical algorithm,whereby confidentiality can be further enhanced for the data.

Further preferably, the mobile communication terminal according to thepresent invention is constructed in a configuration wherein theadditional information contains first encryption key informationnecessary for generation of the first encryption key.

Further preferably, the information processing method according to thepresent invention is configured so that the additional informationcontains first encryption key information necessary for generation ofthe first encryption key.

Further preferably, the data processing program according to the presentinvention is configured so that the additional information containsfirst encryption key information necessary for generation of the firstencryption key.

According to these aspects of the invention, the additional informationencrypted using the second encryption key contains both thefalsification check data and the first encryption key informationnecessary for generation of the first encryption key. Accordingly, itbecomes more difficult to decrypt the additional information. As aresult, the confidentiality is further enhanced for the data. When thecombination of the encryption keys with the encryption key informationis used for encryption of data, it becomes feasible to change theintensity of cipher.

The above was the description of the features about the data encryptiontechnology by the mobile communication terminal as a data transmitter,and the following is the description of the features about the datadecryption technology by the mobile communication terminal as a datareceiver.

A mobile communication terminal according to the present invention is amobile communication terminal for receiving an encryption file from themobile communication terminal as described above, the receiving mobilecommunication terminal comprising: acquiring means for acquiring thedata encrypted by the data encrypting means, the first encryption keyencrypted by the first key encrypting means, and the user-specificinformation from the encryption file; first key decrypting means fordecrypting the first encryption key, using the user-specific informationacquired by the acquiring means; and data decrypting means fordecrypting the data, using the first encryption key decrypted by thefirst key decrypting means.

An information processing method according to the present invention isan information processing method for a mobile communication terminal todecrypt data encrypted by the information processing method as describedabove, the information processing method for decryption comprising: anacquisition step of acquiring the data encrypted in the data encryptionstep, the first encryption key encrypted in the first key encryptionstep, and the user-specific information from the encryption file; afirst key decryption step of decrypting the first encryption key, usingthe user-specific information acquired in the acquisition step; and adata decryption step of decrypting the data, using the first encryptionkey decrypted in the first key decryption step.

A data processing program according to the present invention is a dataprocessing program for letting a computer having data encrypted by thefunctions fulfilled by the data processing program as described above,fulfill: an acquisition function of acquiring the data encrypted by thedata encryption function, the first encryption key encrypted by thefirst key encryption function, and the user-specific information fromthe encryption file; a first key decryption function of decrypting thefirst encryption key, using the user-specific information acquired bythe acquisition function; and a data decryption function of decryptingthe data, using the first encryption key decrypted by the first keydecryption function.

According to these aspects of the invention, the mobile communicationterminal of the data receiver decrypts the encryption file of the datagenerated from the data encrypted using the first encryption key, thefirst encryption key encrypted using the second encryption key, and theuser-specific information. The encryption file is one encrypted so as tomake the analysis of data difficult, in order to prevent theirregularities such as the unauthorized access to or falsification ofthe data by a third party. Accordingly, the data can be transferred withhigh confidentiality from the transmitter mobile communication terminalto the receiver mobile communication terminal.

Another mobile communication terminal according to the present inventionis a mobile communication terminal for receiving an encryption file fromthe mobile communication terminal as described above, the receivingmobile communication terminal comprising: data acquiring means foracquiring the data encrypted by the data encrypting means, theadditional information encrypted by the additional informationencrypting means, and the second encryption key information from theencryption file; second key generating means for generating the secondencryption key, using the second encryption key information acquired bythe data acquiring means; additional information decrypting means fordecrypting the additional information, using the second encryption keygenerated by the second key generating means; first encryption keyinformation acquiring means for acquiring the first encryption keyinformation and the first falsification check data from the additionalinformation decrypted by the additional information decrypting means;first key generating means for generating the first encryption key,using the first encryption key information acquired by the firstencryption key information acquiring means; and data decrypting meansfor decrypting the data acquired by the data acquiring means, using thefirst encryption key generated by the first key generating means.

Another information processing method according to the present inventionis an information processing method for a mobile communication terminalto decrypt data encrypted by the information processing method asdescribed above, the information processing method for decryptioncomprising: a data acquisition step of acquiring the data encrypted inthe data encryption step, the additional information encrypted in theadditional information encryption step, and the second encryption keyinformation from the encryption file; a second key generation step ofgenerating the second encryption key, using the second encryption keyinformation acquired in the data acquisition step; an additionalinformation decryption step of decrypting the additional information,using the second encryption key generated in the second key generationstep; a first encryption key information acquisition step of acquiringthe first encryption key information and the first falsification checkdata from the additional information decrypted in the additionalinformation decryption step; a first key generation step of generatingthe first encryption key, using the first encryption key informationacquired in the first encryption key information acquisition step; and adata decryption step of decrypting the data acquired in the dataacquisition step, using the first encryption key generated in the firstkey generation step.

Another data processing program according to the present invention is adata processing program for letting a computer having data encrypted bythe functions fulfilled by the data processing program as describedabove, fulfill: a data acquisition function of acquiring the dataencrypted by the data encryption function, the additional informationencrypted by the additional information encryption function, and thesecond encryption key information from the encryption file; a second keygeneration function of generating the second encryption key, using thesecond encryption key information acquired by the data acquisitionfunction; an additional information decryption function of decryptingthe additional information, using the second encryption key generated bythe second key generation function; a first encryption key informationacquisition function of acquiring the first encryption key informationand the first falsification check data from the additional informationdecrypted by the additional information decryption function; a first keygeneration function of generating the first encryption key, using thefirst encryption key information acquired by the first encryption keyinformation acquisition function; and a data decryption function ofdecrypting the data acquired by the data acquisition function, using thefirst encryption key generated by the first key generation function.

According to these aspects of the invention, the mobile communicationterminal of the data receiver decrypts the encryption file of the datagenerated from the data encrypted using the first encryption key, theadditional information encrypted using the second encryption key, andthe second encryption key information containing the user-specificinformation. The encryption file is one encrypted so as to make theanalysis of data much more difficult, in order to prevent theirregularities such as the unauthorized access to or falsification ofthe data by a third party. Accordingly, the data can be transferred withmuch higher confidentiality from the transmitter mobile communicationterminal to the receiver mobile communication terminal.

Preferably, the mobile communication terminal according to the presentinvention further comprises second falsification check data generatingmeans for generating second falsification check data for a falsificationcheck on the data decrypted by the data decrypting means; and collatingmeans for collating the first falsification check data acquired by thefirst encryption key information acquiring means, with the secondfalsification check data generated by the second falsification checkdata generating means.

Preferably, the information processing method according to the presentinvention further comprises a second falsification check data generationstep of generating second falsification check data for a falsificationcheck on the data decrypted in the data decryption step; and a collationstep of collating the first falsification check data acquired in thefirst encryption key information acquisition step, with the secondfalsification check data generated in the second falsification checkdata generation step.

Preferably, the data processing program according to the presentinvention makes the computer further fulfill a second falsificationcheck data generation function of generating second falsification checkdata for a falsification check on the data decrypted by the datadecryption function; and a collation function of collating the firstfalsification check data acquired by the first encryption keyinformation acquisition function, with the second falsification checkdata generated by the second falsification check data generationfunction.

According to these aspects of the invention, the second falsificationcheck data is generated for determining whether the decrypted data isfalsified. The second falsification check data generated is collatedwith the first falsification check data. When the result of thecollation is that the two falsification check data items agree with eachother, it is determined that the data as an object for transfer is notfalsified. On the other hand, when the two falsification check dataitems are different from each other., it is determined that the data asan object for transfer can be falsified in the data transfer process.When the mobile communication terminal of the data receiver isconfigured in this way to determine whether the data is falsified, theuser of the mobile communication terminal can readily recognize thevalidity of the transferred data. For example, where there is apossibility that the data is falsified, use of the data (includingreproduction thereof) is prohibited, so as to avoid inconveniences dueto use of the falsified data (authentication failure, virus infection,etc.).

The information processing technology according to the present inventioncan extensively be carried out when a recording medium which a computer(including the mobile communication terminal) can read and which storesthe aforementioned data processing program, is subjected to sale ordistribution as a single unit or as an attached product.

Another potential mobile communication terminal according to the presentinvention is a mobile communication terminal comprising: data encryptingmeans for encrypting data, using a first encryption key; thirdfalsification check data generating means for generating thirdfalsification check data for a falsification check on the firstencryption key; additional information encrypting means for encryptingadditional information containing the third falsification check datagenerated by the third falsification check data generating means, usinga second encryption key; and encryption file generating means forgenerating an encryption file of the data from the data encrypted by thedata encrypting means, the additional information encrypted by theadditional information encrypting means, and second encryption keyinformation containing user-specific information permittingidentification of a user of the mobile communication terminal.

Another potential information processing method according to the presentinvention is an information processing method for a mobile communicationterminal to process data, the information processing method comprising:a data encryption step of encrypting data, using a first encryption key;a third falsification check data generation step of generating thirdfalsification check data for a falsification check on the firstencryption key; an additional information encryption step of encryptingadditional information containing the third falsification check datagenerated in the third falsification check data generation step, using asecond encryption key; and an encryption file generation step ofgenerating an encryption file of the data from the data encrypted in thedata encryption step, the additional information encrypted in theadditional information encryption step, and second encryption keyinformation containing user-specific information permittingidentification of a user of the mobile communication terminal.

Another potential data processing program according to the presentinvention is a data processing program for letting a computer fulfill: adata encrypting function of encrypting data, using a first encryptionkey; a third falsification check data generation function of generatingthird falsification check data for a falsification check on the firstencryption key; an additional information encryption function ofencrypting additional information containing the third falsificationcheck data generated by the third falsification check data generationfunction, using a second encryption key; and an encryption filegeneration function of generating an encryption file of the data fromthe data encrypted by the data encryption function, the additionalinformation encrypted by the additional information encryption function,and second encryption key information containing user-specificinformation permitting identification of a user of a mobilecommunication terminal.

According to these aspects of the invention, the encryption file of thedata is generated from the data encrypted using the first encryptionkey, the additional information containing the third falsification checkdata for the falsification check on the first encryption key, and theuser-specific information. Namely, the generated encryption filecontains both the encrypted data and the first encryption key encryptedafter having been converted for the falsification check, which makes theanalysis of data difficult. This can prevent the irregularities such asthe unauthorized access to or falsification of the data by a third partyin advance. As a result, high confidentiality can be secured for thedata. Since the generated encryption file contains the user-specificinformation permitting the identification of the user of the mobilecommunication terminal, it is feasible to lower the risk that theencryption file is decrypted by mobile communication terminals of otherusers.

In another potential configuration, the encryption file is generatedfrom additional information containing falsification check data for afalsification check on the second encryption key, instead of the firstencryption key.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration showing a whole configuration of adata processing system.

FIG. 2 is a block diagram showing a functional configuration of atransmitter cell phone.

FIG. 3 is a diagram showing an internal configuration of memory part ofthe transmitter cell phone in the first embodiment.

FIG. 4 is an illustration conceptually showing the flow of dataencryption processing executed by the transmitter cell phone in thefirst embodiment.

FIG. 5 is an illustration conceptually showing the flow of datadecryption processing executed by a receiver cell phone in the firstembodiment.

FIG. 6 is a diagram showing a configuration example of key B relatedinformation in the second embodiment.

FIG. 7 is an illustration conceptually showing the flow of dataencryption processing executed by the transmitter cell phone in thesecond embodiment.

FIG. 8A is a diagram showing an internal configuration of the memorypart of the transmitter cell phone in the third embodiment. FIG. 8B is adiagram showing an internal configuration of the memory part of thereceiver cell phone in the third embodiment.

FIG. 9 is an illustration conceptually showing the flow of dataencryption processing executed by the transmitter cell phone in thethird embodiment.

FIG. 10 is an illustration conceptually showing the flow of dataencryption processing executed by the transmitter cell phone in amodification of the third embodiment.

FIG. 11 is an illustration conceptually showing the flow of datadecryption processing executed by the receiver cell phone in the thirdembodiment.

FIG. 12A is a diagram showing an internal configuration of the memorypart of the transmitter cell phone in the fourth embodiment. FIG. 12B isa diagram showing a configuration example of key B related informationin the fourth embodiment.

FIG. 13 is an illustration conceptually showing the flow of dataencryption processing executed by the transmitter cell phone in thefourth embodiment.

FIG. 14 is an illustration conceptually showing the flow of dataencryption processing executed by the transmitter cell phone in amodification of the fourth embodiment.

BEST MODES FOR CARRYING OUT THE INVENTION First Embodiment

The mobile communication terminal in the first embodiment of the presentinvention will be described below with reference to FIGS. 1 to 5.

First, the configuration will be described. FIG. 1 is a schematicillustration showing an example of the whole configuration of dataprocessing system 1 in the present embodiment. As shown in FIG. 1, thedata processing system 1 is generally comprised of transmitter cellphone 10 (corresponding to a mobile communication terminal) and receivercell phone 20 (corresponding to a mobile communication terminal). Thetransmitter cell phone 10 is connected via base station 41 to mobilecommunication network 30 and the receiver cell phone 20 is connected viabase station 42 to mobile communication network 30. The transmitter cellphone 10 and the receiver cell phone 20 are configured to be able totransmit or receive data to or from each other through mobilecommunication network 30. It is assumed in the description of thepresent embodiment hereinafter that one user uses the transmitter cellphone 10 and receiver cell phone 20, envisaging replacement of the UIMupon a switch between models of cell phones, or under such circumstancesthat the user selectively uses a plurality of communication terminals.

The internal configuration of transmitter cell phone 10 will be detailedbelow with reference to FIG. 2. FIG. 2 is a block diagram showing thefunctional configuration of transmitter cell phone 10. As shown in FIG.2, the transmitter cell phone 10 is composed of controller 11(corresponding to the data encrypting means, first key encrypting means,encryption file generating means, first falsification check datagenerating means, additional information encrypting means, and secondkey generating means), input part 12, RAM 13, display part 14, memorypart 15, radio communication part 16 with antenna 16 a, and audioprocessor 17 with microphone 17 a and speaker 17 b, and these parts areconnected through bus 18 so as to be able to implement input/output ofvarious signals.

The controller 11 retrieves a program stored in the memory part 15, intoRAM 13 and performs concentrated control over each part in accordancewith the program. Namely, the controller 11 executes the encryption filegeneration processing including encryption of data as an object fortransfer to the receiver cell phone 20 in accordance with an inputsignal from input part 12 and the program retrieved into the RAM 13, andtemporarily saves the result of the processing into RAM 13. Then thecontroller stores the result of the processing saved in the RAM 13, intoa predetermined area inside the memory part 15 as occasion may demand.

The input part 12 is constructed with various control buttons for givinginstructions such as ON/OFF of power, selection of functions, etc., andthese various control buttons are arranged to be depressed singly or incombination to output an input signal according to the contents ofinstructions to the controller 11.

The RAM (Random Access Memory) 13 is comprised of a volatilesemiconductor memory and is arranged to temporarily save a program ordata retrieved from memory part 15 described below, in various processesexecuted by the controller 11. The RAM 13 also has the function of VRAM(Video RAM) for temporarily saving data under display in the displaypart 14.

The display part 14 is comprised of an LCD (Liquid Crystal Display), anEL (Electro Luminescence), or the like, and is arranged to displaydisplayed data on a screen in accordance with a display signal suppliedfrom the controller 11.

The memory part 15 is comprised of a nonvolatile semiconductor memorysuch as an EEPROM (Electrically Erasable and Programmable ROM) or thelike, and is arranged to store data necessary for execution of variousprocesses, data generated as a result of execution of the variousprocesses, and so on.

As shown in FIG. 3, the memory part 15 internally has data storage area151 a, key A storage area 151 b, key B storage area 151 c, key Binformation storage area 151 d, and key B generation algorithm storagearea 151 e. The data storage area 151 a stores data as an object fortransfer to the receiver cell phone 20, i.e., data to be encrypted. Thedata embraces a file and/or a program and is, for example, userinformation (a name and/or a telephone number of the user), a telephonedirectory, ringing melodies, and so on. The data may be a data groupstored in a folder.

The key A storage area 151 b stores an encryption key (corresponding tothe first encryption key) for encryption of data retrieved from datastorage area 151 a, as “key A.” The key A may be one that was stored inthe key A storage area 151 b, prior to an instruction of encryption ofdata, or one that is generated in conjunction with an encryption startinstruction from the controller 11. The key A can be arbitrarily changedin its setting according to the level of copyright protection and theintensity of encryption for the data to be encrypted.

The key B storage area 151 c stores another encryption key(corresponding to the second encryption key) for encryption of the key Aretrieved from key A storage area 151 b, as “key B.” Data correspondingto user-specific information included in key B information describedlater can be used as it is (without any change or processing), as key B.For example, where the key B information contains the “telephone number”being one of the user-specific information, numerical data of“09012345678” will be stored in the key B storage area 151 c.

Data newly generated in conjunction with an encryption start instructionfrom controller 11 may also be used as key B. Namely, data generated byproperly changing or processing the data corresponding to theuser-specific information included in the after-described key Binformation is used as key B. More specifically, where the key Binformation contains the “telephone number” being one of theuser-specific information, the key B will be defined, for example, bynumerical data of “090123456780901234567809012345678” being a series ofrepetitions of “09012345678.” Therefore, this data is stored in the keyB storage area 151 c.

For this reason, the key B stored by either of the above methods comesto reflect the user-specific information. The key B can be arbitrarilychanged in its setting according to the level of copyright protectionand the intensity of encryption for the data to be encrypted.

The key B information storage area 151 d stores “key B information”containing at least one user-specific information. The user-specificinformation is information for indicating what is the substance of thedata (key B) as an object for acquisition or the data necessary forgeneration of key B, and is not such data itself. For example, where theuser-specific information is the telephone number, such data will benumerical data of “09012345678” indicated by the user-specificinformation of “telephone number.” The user-specific information isinformation permitting identification of the user of transmitter cellphone 10. The user-specific information is preferably information thatcannot be rewritten even by the user of transmitter cell phone 10 andis, for example, the telephone number of transmitter cell phone 10, auser ID, a production number of transmitter cell phone 10, an ID of theUIM detachably mounted on transmitter cell phone 10, or the like.

The key B generation algorithm storage area 151 e stores a key Bgeneration algorithm. The key B generation algorithm is an algorithm forgeneration of key B, which is used only in the case where the key B isnewly generated using the data corresponding to the aforementioneduser-specific information. In the case where there exist a plurality ofuser-specific information items in the key B information, the key Bgeneration algorithm selects some user-specific information items out ofthe plurality of user-specific information items and uses datacorresponding to the selected user-specific information items in thegeneration of key B.

The radio communication part 16 performs control on radio communicationwith base station 41. Specifically, the radio communication part 16 is acircuit having a modulator-demodulator part (not shown) for carrying outmodulation and demodulation of signals, and a coder-decoder (not shown)for performing coding and decoding of signals, and is provided withantenna 16 a. The antenna 16 a is telescopically arranged in the upperpart of the housing of transmitter cell phone 10 and is used intransmission/reception of radio waves to or from base station 41.

The audio processor 17 is comprised of a converter, an amplifier, etc.and is provided with microphone 17 a and speaker 17 b. The audioprocessor 17 converts audio data supplied from controller 11, into ananalog signal in the converter (not shown) and emits sound throughamplification in the amplifier (not shown) from speaker 17 b duringcalls. The audio processor 17 also converts an audio signal suppliedthrough microphone 17 a, into a digital signal by the converter andoutputs the digital signal to controller 11 during calls.

The above described each of the components of transmitter cell phone 10in the present embodiment, and the major configuration of receiver cellphone 20 is the same as the configuration of transmitter cell phone 10;therefore, the illustration and detailed description of theconfiguration is omitted herein. Namely, the receiver cell phone 20 isgenerally comprised of controller 21 (corresponding to the acquiringmeans, first key decrypting means, data decrypting means, data acquiringmeans, second key generating means, additional information decryptingmeans, first encryption key information acquiring means, first keygenerating means, second falsification check data generating means, andcollating means), input part 22, RAM 23, display part 24, memory part25, radio communication part 26 with antenna 26 a, and audio processor27 with microphone 27 a and speaker 27 b. The parts each are connectedthrough bus 28 so as to be able to implement input/output of varioussignals.

The operation of transmitter cell phone 10 in the present embodimentwill be described below, together with the information processing methodaccording to the present invention. Each of steps described below isfulfilled by letting controller 11 execute the program stored in thememory part 15 shown in FIG. 2. The operation will be described on thepremise that “X×Y” indicates data obtained by encrypting “X” using “Y.”For example, “data×key A” indicates data obtained by encrypting datausing key A.

FIG. 4 is an illustration conceptually showing the flow of the dataencryption processing executed by transmitter cell phone 10. First, thecontroller 11 acquires data as an object for encryption from the datastorage area 151 a. Then the controller 11 encrypts the data, using thekey A acquired from the key A storage area 151 b (S11). As a result,“data×key A” is generated.

At S12, the controller 11 acquires or generates the key B. In the casewhere the controller 11 acquires the key B, the controller 11 acquiresthe data corresponding to the user-specific information in the key Binformation from the predetermined area of memory part 15. Thereafter,the above data itself is stored as key B into the key B storage area 151c. For example, where the user-specific information is the telephonenumber of the transmitter cell phone 10, the data of “09012345678” willbe stored into the key B storage area 151 c.

In the case where the controller 11 generates the key B, the controller11 first acquires the key B information from the key B informationstorage area 151 d. Subsequently, it acquires the key B generationalgorithm from the key B generation algorithm storage area 151 e. Thecontroller 11 executes the key B generation algorithm to generate thekey B on the basis of the user-specific information included in theabove key B information. The generated key B is stored into the key Bstorage area 151 c. For example, where the user-specific information isthe telephone number of transmitter cell phone 10, data of a series ofthe predetermined number of repetitions of “09012345678” will be storedinto the key B storage area 151 c. Upon the storage or after thestorage, this key B may be arbitrarily changed according to the level ofcopyright protection and the intensity of encryption for the data to beencrypted.

Furthermore, the controller 11 encrypts the key A, using the key Bacquired from the key B storage area 151 c (S13). As a result, “keyA×key B” is generated.

Then the controller 11 acquires the key B information from key Binformation storage area 151 d and combines the data of “data×key A,”“key A×key B,” and key B information (S14). The term “combine” hereinmeans to generate one or more files from a plurality of data items. As aresult, an encryption file is generated. The transmitter cell phone 10transfers the generated encryption file to the receiver cell phone 20.The transfer of the encryption file can be implemented by any transfermethod; for example, transmission via a server apparatus, transferthrough a recording medium such as the UIM or the like, transfer usingshort-range radio communication such as IrDA (Infrared Data Association)or Bluetooth (registered trademark), and so on.

In the transmitter cell phone 10 of the present embodiment, theencryption file is generated from the data encrypted using the key A(data×key A), the key A encrypted using the key B (key A×key B), and thekey B information. Namely, the encryption file is generated throughdouble encryption processes, so that the analysis of the data becomesmore difficult than that of encryption files generated throughencryption using a non-encrypted encryption key. This prevents theirregularities such as the unauthorized access to or falsification ofthe data by a third party in advance. As a result, high confidentialitycan be secured for the data. Since the generated encryption filecontains the user-specific information permitting identification of theuser of the transmitter cell phone 10, the encryption file is at lowrisk of being decrypted by other users.

The following is the description of the operation of receiver cell phone20 in the present embodiment. Each of steps described below is fulfilledby letting the controller 21 execute the program stored in the memorypart 25. FIG. 5 is an illustration conceptually showing the flow of thedata decryption processing executed by the receiver cell phone 20.First, the receiver cell phone 20 acquires the encryption file fromtransmitter cell phone 10. Subsequently, the controller 21 separates theacquired encryption file into the data of “data×key A,” “key A×key B,”and key B information (T11). The term “separate” herein means togenerate a plurality of data items from one or more files.

Subsequently, the controller 21 acquires the key B generation algorithmfrom the key B generation algorithm storage area 151 e. Then thecontroller 21 acquires or generates the key B by the aforementionedmethod on the basis of the user-specific information in the key Binformation acquired at T11, using the key B generation algorithm (T12).The controller 21 decrypts “key A×key B,” using this key B (T13). As aconsequence, the key A is generated. Then the controller 21 decrypts“data×key A,” using the generated key A (T14). As a result, the data,which was stored in the data storage area 151 a, is restored.

The receiver cell phone 20 of the present embodiment is configured todecrypt the encryption file of the data generated from the dataencrypted using the key A, the key A encrypted using the key B, and thekey B information. The encryption file is one encrypted so as to makethe analysis of the data difficult, in order to prevent theirregularities such as the unauthorized access to or falsification ofthe data by a third party. Accordingly, the transfer of data can beimplemented with high confidentiality from the transmitter cell phone 10to the receiver cell phone 20.

Second Embodiment

The mobile communication terminal in the second embodiment of thepresent invention will be described below with reference to FIGS. 6 and7. Since the fundamental configuration of the data processing system inthe present embodiment is much the same as that of the data processingsystem 1 in the first embodiment, the same reference symbols will denotethe corresponding components, without description thereof, and onlydifferences from the first embodiment will be detailed below.

The second embodiment is based on a form of generating the key B bychanging or processing the data corresponding to the user-specificinformation. The transmitter cell phone 10 in the second embodiment isdifferent from the transmitter cell phone in the first embodiment inthat a plurality of key B generation algorithms are stored in the key Bgeneration algorithm storage area 151 e shown in FIG. 3 and in that akey B generation algorithm is properly selected and used out of thosekey B generation algorithms.

FIG. 6 is a diagram showing a configuration example of key B relatedinformation 251 stored in the key B information storage area 151 d (cf.FIG. 3). As shown in FIG. 6, the key B related information 251 isconfigured containing at least header 251 a, key B information 251 b,and key B generation algorithm information 251 c.

The header 251 a stores information indicating locations of storage ofthe key B information 251 b and the key B generation algorithminformation 251 c. Namely, the controller 11 extracts the key Binformation 251 b and the key B generation algorithm information 251 cfrom the key B related information 251 with reference to the header 251a.

The key B information 251 b stores “key B information” necessary forgeneration of the key B (corresponding to the second encryption key).This key B information (corresponding to the second encryption keyinformation) contains at least one user-specific information permittingidentification of the user of transmitter cell phone 10. Theuser-specific information is, for example, the telephone number oftransmitter cell phone 10, the user ID, the production number oftransmitter cell phone 10, the ID of the UIM, or the like.

The key B generation algorithm information 251 c stores information foridentification of a predetermined key B generation algorithm(corresponding to the identification information) among the plurality ofkey B generation algorithms stored in the key B generation algorithmstorage area 151 e. Namely, the controller 11 selects an algorithm usedin generation of the key B, out of the plurality of key B generationalgorithms, based on this key B generation algorithm information.

Furthermore, dummy data not used for encryption is put in areas (areasindicated by “ . . . ” in the figure) except for the header 251 a, key Binformation 251 b, and key B generation algorithm information 251 c.This makes it difficult to extract the key B information 251 b and key Bgeneration algorithm information 251 c, without reference to the header251 a, and thus enhances the confidentiality of the key B relatedinformation. The locations of storage of the key B information 251 b andkey B generation algorithm information 251 c can be those arbitrarilychangeable, or those fixed.

The key B generation algorithm storage area 15le stores a plurality ofkey B generation algorithms as detailed in the first embodiment.

The following is the description of the operation of transmitter cellphone 10 in the present embodiment, together with the informationprocessing method according to the present invention. FIG. 7 is adiagram conceptually showing the flow of the data encryption processingexecuted by the transmitter cell phone 10. The operation of transmittercell phone 10 in the present embodiment is different in the process ofS12.

At S12, the controller 11 acquires the key B related information 251from the key B information storage area 151 d. Subsequently, thecontroller 11 acquires the key B information 251 b and the key Bgeneration algorithm information 251 c with reference to the header 251a included in the acquired key B related information 251. Furthermore,the controller 11 selects and acquires the key B generation algorithmidentified by the key B generation algorithm information 251 c, out ofthe plurality of key B generation algorithms stored in the key Bgeneration algorithm storage area 151 e. Then the controller 11generates the key B from the data corresponding to the user-specificinformation in the key B information acquired from the key B informationstorage area 151 d, using the key B generation algorithm acquired fromthe key B generation algorithm storage area 151 e.

In the transmitter cell phone 10 of the present embodiment, the key B isgenerated using the algorithm identified by the key B generationalgorithm information. Accordingly, the algorithm used is changedaccording to the key B generation algorithm information. This canfurther enhance the confidentiality for the data while making it moredifficult for a third party to specify the used algorithm than in thecase where the key B is always generated using the same algorithm.

Third Embodiment

The data processing system in the third embodiment of the presentinvention will be described below with reference to FIGS. 8 to 11. Sincethe fundamental configuration of the data processing system in thepresent embodiment is much the same as that of the data processingsystem 1 in the first embodiment, the same reference symbols will denotethe corresponding components, without description thereof, and onlydifferences from the first embodiment will be detailed below. The dataprocessing system 1 in the present embodiment is different in theinternal configurations of memory part 15 of transmitter cell phone 10and memory part 25 of receiver cell phone 20 from the data processingsystem 1 in the first embodiment.

Namely, as shown in FIG. 8A, the memory part 15 internally has datastorage area 152 a, key A information storage area 152 b, key Ageneration algorithm storage area 152 c, falsification check algorithmstorage area 152 d, data list storage area 152 e, key B informationstorage area 152 f, and key B generation algorithm storage area 152 g.

The data storage area 152 a stores data as an object for transfer toreceiver cell phone 20, i.e., data as an object for encryption. The dataembraces a file and/or a program and is, for example, the userinformation (the name and/or the telephone number of the user), thetelephone directory, the ringing melodies, or the like. The data may bea data group stored in a folder.

The key A information storage area 152 b stores “key A information”necessary for generation of the key A (corresponding to the firstencryption key). This key A information (corresponding to the firstencryption key information) can be any information, for example, such asthe telephone number of transmitter cell phone 10, the user ID, theproduction number of transmitter cell phone 10, a time, a random number,or the like, but it is desirable to use information different fromafter-described key B information in view of the difficulty in theanalysis of data.

The key A generation algorithm storage area 152 c stores “key Ageneration algorithm” which is an algorithm for generation of the key A,using the key A information.

The falsification check algorithm storage area 152 d stores afalsification check algorithm which is an algorithm for generation offalsification check data 1 (corresponding to the first falsificationcheck data) from the data retrieved from data storage area 152 a. Thefalsification check algorithm is, for example, a hash function and, morespecifically, is one of MD (Message Digest) 2, MD4, MD5, SHA (SecureHash Algorithm)-1, and so on.

In the case where the data is stored in a folder, the data list storagearea 152 e stores as “data list” a list of information (a name, anidentification number, etc.) for identification of the data stored inthe folder.

The key B information storage area 152 f stores the “key B information”necessary for generation of the key B (corresponding to the secondencryption key). This key B information (corresponding to the secondencryption key information) contains at least one user-specificinformation permitting identification of the user of the transmittercell phone 10. The user-specific information is information that cannotbe rewritten even by the user of the transmitter cell phone 10 and is,for example, the telephone number of transmitter cell phone 10, the userID, the production number of transmitter cell phone 10, the ID of theUIM, or the like.

The key B generation algorithm storage area 152 g stores the “key Bgeneration algorithm” which is an algorithm for generation of the key Busing the key B information.

As shown in FIG. 8B, the memory part 25 internally has key B generationalgorithm storage area 252 a, key A generation algorithm storage area252 b, and falsification check algorithm storage area 252 c.

The key B generation algorithm storage area 252 a stores the “key Bgeneration algorithm” which is an algorithm for generation of the key Busing the key B information.

The key A generation algorithm storage area 252 b stores the “key Ageneration algorithm” which is an algorithm for generation of the key Ausing the key A information.

The falsification check algorithm storage area 252 c stores thefalsification check algorithm which is an algorithm for generation offalsification check data 2 (corresponding to the second falsificationcheck data) from decrypted data. The falsification check algorithm is,for example, a hash function and, more specifically, it is one of MD(Message Digest) 2, MD4, MD5, SHA (Secure Hash Algorithm)-1, and so on.

The operation of transmitter cell phone 10 in the present embodimentwill be described below, together with the information processing methodaccording to the present invention. Each of steps described below isfulfilled by letting the controller 11 execute the program stored in thememory part 15 shown in FIG. 2.

FIG. 9 is a diagram conceptually showing the flow of the data encryptionprocessing executed by the transmitter cell phone 10. First, thecontroller 11 acquires the key A information from the key A informationstorage area 152 b. The controller 11 also acquires the key A generationalgorithm from the key A generation algorithm storage area 152 c. Thenthe controller 11 generates the key A from the key A informationacquired from the key A information storage area 152 b, using the key Ageneration algorithm acquired from the key A generation algorithmstorage area 152 c (S21). Upon the generation or after the generation,this key A may be arbitrarily changed according to the level ofcopyright protection and the intensity of encryption for the data to beencrypted.

Subsequently, the controller 11 acquires data as an object forencryption from the data storage area 152 a. Then the controller 11encrypts the data, using the key A generated at S21 (S22). As a result,“data×key A” is generated.

On the other hand, the controller 11 acquires the falsification checkalgorithm from the falsification check algorithm storage area 152 d andgenerates the falsification check data 1 from the data acquired from thedata storage area 152 a, using the falsification check algorithm (S23).For example, where the falsification check algorithm is a hash function,the falsification check data 1 will correspond to the hash value.

The controller 11 combines the data items of falsification check data 1generated at S23, the data list acquired from the data list storage area152 e, and the key A information acquired from the key A informationstorage area 152 b (S24). The term “combine” herein means to generateone or more files from a plurality of data items. This results ingenerating additional information containing the falsification checkdata 1, the data list, and the key A information.

Subsequently, the controller 11 acquires the key B information from keyB information storage area 152 f. The controller 11 also acquires thekey B generation algorithm from the key B generation algorithm storagearea 152 g. Then the controller 11 generates the key B from the key Binformation acquired from the key B information storage area 152 f,using the key B generation algorithm acquired from the key B generationalgorithm storage area 152 g (S25). Upon the generation or after thegeneration, this key B may be arbitrarily changed according to the levelof copyright protection and the intensity of encryption for the data tobe encrypted.

Then the controller 11 encrypts the additional information generated atS24, using the key B generated at S25 (S26). As a result, “additionalinformation×key B” is generated.

Thereafter, the controller 11 acquires the key B information from thekey B information storage area 152 f and combines the data items of“data×key A,” “additional information×key B,” and key B information(S27). As a result, an encryption file is generated. The transmittercell phone 10 transfers the generated encryption file to receiver cellphone 20. The transfer of the encryption file can be implemented by anytransfer method; for example, transmission via a server apparatus,transfer through a recording medium such as the UIM or the like,short-range radio communication such as IrDA (Infrared Data Association)or Bluetooth (registered trademark), and so on.

The controller 11 may be configured at S26 to extract the data list fromthe additional information and encrypt only the additional informationexcept for the data list. In this case, the data list is attached in anon-encrypted state to the additional information and thereafter isincorporated into the encryption file. This decreases the load on thetransmitter cell phone 10 due to the data encryption processing. It alsodecreases the volume of data of the encryption file and thus saves thefree space of memory part 15.

In the transmitter cell phone 10 of the present embodiment, theencryption file is generated from the data encrypted using the key A,the additional information containing the falsification check data 1 forthe falsification check on the data, and the key B information. Namely,the generated encryption file contains both the encrypted data and thedata encrypted after having been converted for the falsification check,which makes the analysis of data difficult. As a result, higherconfidentiality is secured for the data. Since the generated encryptionfile contains the key B information containing the informationpermitting identification of the user of the transmitter cell phone 10,it is at low risk of being decrypted by other users.

In the transmitter cell phone 10 of the present embodiment, the key B isgenerated using the key B information containing the informationpermitting identification of the user of the transmitter cell phone 10.The additional information containing the falsification check data 1 isencrypted using the key B. Namely, the information permitting theidentification of the user is essential to decryption of the additionalinformation. Accordingly, the encryption file is at low risk of beingdecrypted by other users, as a matter of course, and the additionalinformation is also at low risk of being decrypted by other users. Thispermits much higher confidentiality to be secured for the data.

Here FIG. 10 is a diagram conceptually showing the flow of dataencryption processing in a modification of the third embodiment. In thethird embodiment, the target for the falsification check by thefalsification check algorithm was the data as an object for encryption.However, as shown in FIG. 10, the key A generated at S21 can be used asa target for the falsification check, or the key B generated at S25 canbe used as a target for the falsification check. This results ingenerating falsification check data 3 (corresponding to the thirdfalsification check data) through conversion of key A or key B for thefalsification check.

The key A or key B is normally lower in volume than the aforementioneddata, and thus makes the falsification check easier. Accordingly, theprocessing load due to the falsification check is reduced on thetransmitter cell phone 10. Since the falsification check data generatedfrom the key A or the key B of the lower volume than the above data alsohas a lower volume, it can save the free space of memory part 15. Thisform is suitably applicable particularly to cases not requiring a sohigh security level for data transfer.

The following is the description of the operation of receiver cell phone20 in the present embodiment. Each of steps described below is fulfilledby letting the controller 21 execute the program stored in the memorypart 25. FIG. 11 is a diagram conceptually showing the flow of the datadecryption processing executed by receiver cell phone 20. First, thereceiver cell phone 20 acquires the encryption file from the transmittercell phone 10. Subsequently, the controller 21 separates the acquiredencryption file into the data items of key B information, “additionalinformation×key B,” and “data×key A” to acquire them (T21).

Thereafter, the controller 21 acquires the key B generation algorithmfrom the key B generation algorithm storage area 252 a. Then thecontroller 21 generates the key B from the key B information acquired atT21, using the key B generation algorithm acquired from the key Bgeneration algorithm storage area 252 a (T22).

Then the controller 21 decrypts “additional information×key B” acquiredat T21, using the key B generated at T22 (T23). As a result, theadditional information, which was encrypted at S26 in FIG. 9, isrestored. The controller 21 separates the additional information intothe data items of the falsification check data 1, the data list, and thekey A information to acquire them (T24).

The controller 21 acquires the key A generation algorithm from the key Ageneration algorithm storage area 252 b. Then the controller 21generates the key A from the key A information acquired at T24, usingthe key A generation algorithm acquired from the key A generationalgorithm storage area 252 b (T25).

Then the controller 21 decrypts “data×key A” acquired at T26, using thekey A generated at T25 (T26). As a result, the data encrypted bytransmitter cell phone 10 is restored.

The receiver cell phone 20 in the present embodiment decrypts theencryption file of the data generated from the data encrypted using thekey A, the additional information encrypted using the key B, and the keyB information containing the user-specific information. The encryptionfile is one encrypted so as to make the analysis of data much moredifficult, in order to prevent the irregularities such as theunauthorized access to or falsification of the data by a third party.Accordingly, the data transfer can be implemented with much higherconfidentiality from the transmitter cell phone 10 to the receiver cellphone 20.

Furthermore, the receiver cell phone 20 in the present embodimentperforms the processing described below, for judging the identitybetween decrypted data and encrypted data. Namely, the controller 21acquires the falsification check algorithm from the falsification checkalgorithm storage area 252 c. The controller 21 generates falsificationcheck data 2 from the data decrypted at T26, using the acquiredfalsification check algorithm (T27). For example, where thefalsification check algorithm is a hash function, the falsificationcheck data 2 will correspond to the hash value.

Finally, the controller 21 compares and collates the falsification checkdata 1 acquired from the additional information at T24, with thefalsification check data 2 generated at T27 to determine the identity ofthe falsification check data. When the result of the comparisoncollation is that the two falsification check data items agree with eachother, the controller 21 determines that no falsification is made on thedata as an object for transfer. On the other hand, when the twofalsification check data items disagree, the controller 21 determinesthat there is a possibility that the data as an object for transfer isfalsified during the data transfer process.

When the receiver cell phone 20 is configured to determine the presenceor absence of falsification on the data in this way, the user of thereceiver cell phone 20 is allowed to readily recognize the validity oftransferred data. For example, if there is a possibility that the datais falsified, use of the data (including reproduction thereof) will beprohibited, so as to circumvent the inconveniences (authenticationfailure, virus infection, etc.) due to use of the falsified data.

Fourth Embodiment

The fourth embodiment of the present invention will be described belowwith reference to FIGS. 12 to 14. Since the configuration of the dataprocessing system in the present embodiment is much the same as theconfiguration of data processing system 1 in the third embodiment, thesame reference symbols will denote the corresponding components, withoutdescription thereof, and only differences from the third embodiment willbe detailed below. The data processing system 1 of the presentembodiment is different in the internal configuration of memory part 15in the transmitter cell phone 10 from the data processing system 1 ofthe third embodiment.

Namely, as shown in FIG. 12A, the memory part 15 internally has datastorage area 153 a, key A information storage area 153 b, key Ageneration algorithm storage area 153 c, falsification check algorithmstorage area 153 d, data list storage area 153 e, key B informationstorage area 153 f, key B generation algorithm storage area 153 g, andfalsification check algorithm information storage area 153 h.

The present embodiment will be described as to the falsification checkalgorithm information storage area 153 h, which is the structuraldifference from the memory part 15 in the third embodiment. Thefalsification check algorithm information storage area 153 h storesinformation for identification of falsification check algorithms.Namely, the falsification check algorithm storage area 153 d stores aplurality of falsification check algorithms, and the controller 11selects an algorithm to be used in a falsification check, based on thefalsification check algorithm information, out of the plurality offalsification check algorithms.

FIG. 12B is a diagram showing a configuration example of key B relatedinformation 154 stored in the key B information storage area 153 f. Asshown in FIG. 12B, the key B related information 154 is constructedcontaining at least header 154 a, key B information 154 b, and key Bgeneration algorithm information 154 c.

The header 154 a stores information indicating locations of storage ofthe key B information 154 b and the key B generation algorithminformation 154 c. Namely, the controller 11 extracts the key Binformation 154 b and the key B generation algorithm information 154 cfrom the key B related information 154 with reference to the header 154a.

The key B information 154 b stores “key B information” necessary forgeneration of key B (corresponding to the second encryption key). Thiskey B information (corresponding to the second encryption keyinformation) contains at least one user-specific information permittingidentification of the user of transmitter cell phone 10. Theuser-specific information is, for example, the telephone number oftransmitter cell phone 10, the user ID, the production number oftransmitter cell phone 10, the ID of the UIM, or the like.

The key B generation algorithm information 154 c stores information(corresponding to the identification information) for identification ofthe predetermined key B generation algorithm among the plurality of keyB generation algorithms stored in the key B generation algorithm storagearea 153 g. Namely, the controller 11 selects an algorithm used ingeneration of key B out of the plurality of key B generation algorithms,based on the key B generation algorithm information.

Furthermore, dummy data not used in encryption is put in the areas otherthan the header 154 a, key B information 154 b, and key B generationalgorithm information 154 c (i.e., in the areas indicated by “ . . . ”in the figure). This makes it difficult to extract the key B information154 b and the key B generation algorithm information 154 c, withoutreference to header 154 a, and thus enhances the confidentiality of thekey B related information. The storage locations of the key Binformation 154 b and key B generation algorithm information 154 c maybe those arbitrarily changeable, or those fixed.

The above described the configuration of key B related information 154stored in the key B information storage area 153 f, and in the presentembodiment the key A related information of a configuration similar tothat of the key B related information 154 is also stored in the key Ainformation storage area 153 b.

The operation of transmitter cell phone 10 in the present embodimentwill be described below. FIG. 13 is a diagram conceptually showing theflow of the data encryption processing executed by the transmitter cellphone 10. The operation of transmitter cell phone 10 in the presentembodiment is much the same in the major part as that of the transmittercell phone 10 detailed in the third embodiment. Namely, S31-S37 shown inFIG. 13 correspond to S21-S27 shown in FIG. 9. The following is thedescription of S31, S33, S34, and S35 which are processes different fromthose in the third embodiment.

At S31, the controller 11 first acquires the key A related informationfrom the key A information storage area 153 b. Subsequently, thecontroller 11 acquires the key A information and key A generationalgorithm information with reference to the header included in theacquired key A related information. Furthermore, the controller 11selects and acquires the key A generation algorithm identified by thekey A generation algorithm information, out of the plurality of key Ageneration algorithms stored in the key A generation algorithm storagearea 153 c, based on the key A generation algorithm information. Thenthe controller 11 generates the key A from the key A informationacquired from the key A information storage area 153 b, using the key Ageneration algorithm acquired from the key A generation algorithmstorage area 153 c.

At S33, the controller 11 acquires the falsification check algorithminformation from the falsification check algorithm information storagearea 153 h. Subsequently, the controller 11 selects and acquires thefalsification check algorithm identified by the falsification checkalgorithm information, out of the plurality of falsification checkalgorithms stored in the falsification check algorithm storage area 153d, based on the acquired falsification check algorithm information. Thenthe controller 11 generates falsification check data from the dataacquired from the data storage area 153 a, using the acquiredfalsification check algorithm.

At S34, the controller 11 combines the data items of the falsificationcheck data 1 generated at S33, the data list acquired from the data liststorage area 153 e, the key A information acquired from the key Ainformation storage area 153 b, and the falsification check algorithminformation acquired at S33. This results in generating additionalinformation containing the falsification check data 1, the data list,the key A information, and the falsification check algorithminformation.

Furthermore, at S35, the controller performs a process similar to S31about the key B related information. Namely, the controller 11 acquiresthe key B related information from the key B information storage area153 f. Subsequently, the controller 11 acquires the key B informationand the key B generation algorithm information with reference to theheader included in the acquired key B related information. Furthermore,the controller 11 selects and acquires the key B generation algorithmidentified by the key B generation algorithm information, out of theplurality of key B generation algorithms stored in the key B generationalgorithm storage area 153 g, based on the key B generation algorithminformation. Then the controller 11 generates the key B from the key Binformation acquired from the key B information storage area 153 f,using the key B generation algorithm acquired from the key B generationalgorithm storage area 153 g.

S36 may be configured so that the controller 11 extracts the data listfrom the additional information and encrypts only the additionalinformation except for the data list. In this case, the data list isattached in a non-encrypted state to the additional information andthereafter incorporated into the encryption file. This reduces the loadon the transmitter cell phone 10 due to the data encryption processing.It also decreases the data volume of the encryption file and thus savesthe free space of memory part 15.

In the transmitter cell phone 10 of the present embodiment, the key A isgenerated using the algorithm identified by the identificationinformation included in the key A information. Similarly, the key B isgenerated using the algorithm identified by the identificationinformation included in the key B information. The data is convertedinto the falsification check data, using the algorithm identified by thefalsification check algorithm information. Accordingly, the usedalgorithms are changed according to the types of the key A information,key B information, and falsification check algorithm information. Thismakes it more difficult for a third party to specify the usedalgorithms, and further enhances the confidentiality for the data, ascompared with the case where the key A, key B, and falsification checkdata are always generated using the same algorithms.

Here FIG. 14 is a diagram conceptually showing the flow of dataencryption processing in a modification of the fourth embodiment. In thefourth embodiment the target for the falsification check by the selectedfalsification check algorithm was the data as an object for encryption.However, as shown in FIG. 14, the key A generated at S31 may be definedas a target for the falsification check, or the key B generated at S35may be defined as a target for the falsification check. This results ingenerating falsification check data 3 through conversion of the key A orthe key B for the falsification check.

The key A or the key B is normally lower in volume than the above dataand thus makes the falsification check easier. Accordingly, thisconfiguration decreases the processing load on the transmitter cellphone 10 due to the falsification check. Since the volume is low of thefalsification check data generated from the key A or the key B with thelower volume than the above data, the free space of memory part 15 canbe saved. This configuration is suitably applicable particularly tocases not requiring a so high security level during transfer of data.

The forms described in the above embodiments are just preferred examplesof the data processing system according to the present invention, and itis noted that the present invention is by no means intended to belimited to these forms. For example, it was described in each of theabove embodiments that the encryption key and the decryption key werethe same key (private key cryptography), but they may be different keys(public key cryptography).

Lastly, the below will describe a data processing program according tothe present invention, and a computer-readable recording medium(hereinafter simply referred to as “recording medium”) containing arecord of the program. Here the recording medium is a medium that caninduce states of change of energy such as magnetism, light, electricity,or the like in accordance with the description contents of the dataprocessing program against a reading device provided as a hardwareresource in a general-purpose computer or the like and that can transmitthe description contents of the data processing program in the format ofsignals corresponding to the change states to the reading device. Suchrecording media include, for example, media detachably mounted oncomputers (including cell phones, PHSs, etc.) like IC cards such as theUIM or the like, magnetic disks, optical disks, and magnetoopticaldisks, and also include HDs (Hard Disks) fixedly incorporated in thecomputers, nonvolatile semiconductor memories of firmware or the likeintegrally secured, and so on.

The data processing program according to the present invention may beconfigured so that part or all thereof is transmitted through atransmission medium such as a communication line or the like fromanother device to be received and recorded by the radio communicationpart 16 or the radio communication part 26. Conversely, the dataprocessing program according to the present invention may also beconfigured to be transmitted through the transmission medium and beinstalled in another device.

INDUSTRIAL APPLICABILITY

In the mobile communication terminal, information processing method,data processing program, and recording medium according to the presentinvention, the encryption file of data is generated from the dataencrypted using the first encryption key, the first encryption keyencrypted using the second encryption key, and the user-specificinformation. Namely, the encryption file is generated through the doubleencryption processes and this makes the analysis of the data moredifficult than that of encryption files encrypted using a non-encryptedencryption key. This can prevent the irregularities such as theunauthorized access to or falsification of the data by a third party inadvance. As a result, high confidentiality can be secured for the data.Since the generated encryption file contains the user-specificinformation permitting identification of the user of the mobilecommunication terminal, the encryption file is at low risk of beingdecrypted by mobile communication terminals of other users.

1. A mobile communication terminal having a user associated therewithcomprising: a controller; a data encrypting unit configured to encryptdata using a first encryption key; a second key generating unitconfigured to generate a second encryption key using a pre-determinedalgorithm and user-specific information permitting identification of theuser associated with the mobile communication terminal; a firstfalsification check data generating unit configured to generate firstfalsification check data used for a falsification check on the data; anadditional information encrypting unit configured to encrypt, using thesecond encryption key, additional information containing the generatedfirst falsification check data; an encryption file generating unitconfigured to generate an encryption file comprising the encrypted data,the encrypted additional information, and the user-specific informationpermitting identification of the user associated with the mobilecommunication terminal used to generate the second encryption key; atransferring unit configured to transfer the generated encryption fileincluding the encrypted data, the encrypted additional information, andthe user-specific information to a receiver mobile communicationterminal storing the pre-determined algorithm; a data acquiring unitconfigured to acquire the encrypted data, the encrypted additionalinformation, and a second encryption key information from the encryptionfile; a second key generating unit configured to generate the secondencryption key using the acquired second encryption key information; anadditional information decrypting unit configured to decrypt theadditional information using the generated second encryption key; afirst encryption key information acquiring unit configured to acquire afirst encryption key information and the first falsification check datafrom the decrypted additional information; a first key generating unitconfigured to generate the first encryption key using the acquired firstencryption key information; and a data decrypting unit configured todecrypt the acquired encrypted data using the generated first encryptionkey, wherein the receiver mobile communication terminal is able todecrypt the encrypted data by using the encrypted additionalinformation, the user-specific information and the pre-determinedalgorithm, wherein an encryption key information contains identificationinformation for identification of an algorithm used in generation of thesecond encryption key, wherein the second key generating unit is furtherconfigured to generate the second encryption key using the algorithmidentified by the identification information, and wherein the additionalinformation contains a data list and first encryption key informationnecessary for generation of the first encryption key.
 2. The mobilecommunication terminal according to claim 1, further comprising: asecond falsification check data generating unit configured to encryptsecond falsification check data used for a falsification check on thedecrypted data; and a collating unit configured to collate the acquiredfirst falsification check data, with the generated second falsificationcheck data.
 3. An information processing method for a mobilecommunication terminal having a user associated therewith to processdata, said information processing method comprising: encrypting datausing a first encryption key; generating second encryption key using apre-determined algorithm and user-specific information permittingidentification of the user associated with the mobile communicationterminal; generating first falsification check data used for afalsification check on the data; encrypting additional informationcontaining the first falsification check data generated in the firstfalsification check data generation step, using the second encryptionkey; generating an encryption file comprising the encrypted data, theencrypted additional information, and the user-specific informationpermitting identification of the user associated with the mobilecommunication terminal used to generate the second encryption key;transferring the generated encryption file including the encrypted data,the encrypted additional information, and the user-specific informationto a receiver mobile communication terminal storing the pre-determinedalgorithm; decrypting, at the receiver mobile communication terminal,the encrypted data using the encrypted additional information, theuser-specific information and the pre-determined algorithm; acquiringthe encrypted data, the encrypted additional information, and a secondencryption key information from the encryption file; generating thesecond encryption key using the acquired second encryption keyinformation; decrypting the additional information using the generatedsecond encryption key; acquiring a first encryption key information andthe first falsification check data from the decrypted additionalinformation; generating the first encryption key using the firstencryption key information acquired in the prior acquiring step; and adata decryption step of decrypting the acquired encrypted data using thegenerated first encryption key, wherein an encryption key informationcontains identification information for identification of an algorithmused in generating the second encryption key, wherein the generatingsecond encryption key further generates the second encryption key usingthe algorithm identified by the identification information, and whereinthe additional information contains a data list and first encryption keyinformation necessary for generating the first encryption key.
 4. Acomputer readable storage medium including a data processing program forexecuting a method for a mobile communication terminal having a userassociated therewith to process data, the method comprising: encryptingdata using a first encryption key; generating second encryption keyusing a pre-determined algorithm and user-specific informationpermitting identification of the user associated with the mobilecommunication terminal; generating first falsification check data usedfor a falsification check on the data; encrypting additional informationcontaining the first falsification check data generated in the firstfalsification check data generation step, using the second encryptionkey; generating an encryption file comprising the encrypted data, theencrypted additional information, and the user-specific informationpermitting identification of the user associated with the mobilecommunication terminal used to generate the second encryption key;transferring the generated encryption file including the encrypted data,the encrypted additional information, and the user-specific informationto a receiver mobile communication terminal storing the pre-determinedalgorithm; decrypting, at the receiver mobile communication terminal,the encrypted data using the encrypted additional information, theuser-specific information and the pre-determined algorithm; acquiringthe encrypted data, the encrypted additional information, and a secondencryption key information from the encryption file; generating thesecond encryption key using the acquired second encryption keyinformation; decrypting the additional information using the generatedsecond encryption key; acquiring a first encryption key information andthe first falsification check data from the decrypted additionalinformation; generating the first encryption key using the acquiredfirst encryption key information; and decrypting the acquired data usingthe generated first encryption key, wherein an encryption keyinformation contains identification information for identification of analgorithm used in generating the second encryption key, wherein thegenerating second encryption key further generates the second encryptionkey using the algorithm identified by the identification information,and wherein the additional information contains a data list and firstencryption key information necessary for generating the first encryptionkey.